'The Voice' Fakery! Gwen & Blake Play Nice For The Cameras, Battle Behind The Scenes

The Voice judges Gwen Stefani and Blake Shelton are one of reality TV's most loved-up couples, but RadarOnline.com has learned that behind the scenes, they're putting on an entirely different show!

“They are not as loving towards each other behind the scenes,” an on-set snitch told Radar. “Gwen often looks irritated by him backstage and she is not constantly smiling at Blake like she is when they are taping.”

As previously reported, Stefani, 47, and her 40-year-old country crooner hunk were reprimanded by NBC execs last week when the “Make Me Love You” singer flirted with a contestant on-air, prompting jealous Shelton to lash out.

Stefani clearly learned her lesson, because this week she blabbed on-air that she and Shelton have a “make out playlist” after Team Stefani member, Hunter Plake, performed a cover to “I Want To Know What Love Is” by Foreigner.

After Shelton told his lady love, “I told you I knew that song,” judge Adam Levine, 38, screamed, “Ew!" – while judge Alicia Keys, 36, told Stefani, “That’s cute Gwen!”

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And although the whole incident seemed authentic to viewers, the insider insisted that it was not!

“This is just not how they are when cameras are off,” the source told Radar. “Gwen can actually be quite moody and she is not always the happy-go-lucky person that she likes the public to believe she is.”